COMB FILTERS BASED ON SUPERSTRUCTURE ROCKING FILTERS IN PHOTOSENSITIVE OPTICAL FIBERS

We have fabricated superstructure rocking filters which operate on the principle of linear polarization rotation through the twisting of the birefringent axes of photosensitive elliptical-core fibers by UV radi ation. The polarization coupling spectrum of these filters consists of a series of narrow resonances which are roughly equally spaced in fre quency. This can result in a comb-like response extending over the ent ire single-mode frequency range of the fiber. Applications of such str uctures are also discussed. (C) 1997 Published by Elsevier Science B.V .